Citrix XenServer is a Type 1 hypervisor, also known as a bare-metal hypervisor. It is installed directly on the physical server's hardware and manages the hardware and guest operating systems. This type of hypervisor provides high performance and stability because it does not run inside another operating system but acts as a lightweight operating system itself designed to run virtual machines. Citrix XenServer is based on the open-source Xen Project hypervisor and is optimized for server, desktop, and cloud virtualization infrastructures. References: The information is supported by the official Citrix documentation1 and further details can be found in the Citrix Hypervisor technical overview